The new Loader detects much more information about columns and sets flags like is_auto_increment that it didn't set before.

RelBuilder

The new RelBuilder will give you nicer accessor names for relationships,
so you will no longer have conflicts between a foreign key column and the relationship accessor itself (if the FK is named _id.)

It will also more correctly infer the relationship type,
e.g.
some relationships that were previously detected as a has_many will now be a might_have (when it detects a unique constraint on the foreign key column.)

Also cascade_delete and cascade_copy are turned off for by default for has_many and might_have relationships,
while belongs_to relationships are created with on_delete => 'CASCADE' and on_update => 'CASCADE' by default.
This is overridable via relationship_attrs.

moniker_map

Table names are now singularized when determining the Result class names.
So the table user_roles would have become UserRoles in 0.04006 but now becomes UserRole instead.

When reading a Schema.pm from a static schema generated with an 0.04 version of Loader,
backward compatibility mode will default to on,
unless overridden with the naming and/or use_namespaces attributes.